The  subject  Theory  of  Machines  may  be  defined  as  that  branch  of

Engineering-science, which deals with the study of relative motion between the various parts of

a machine, and forces which act on them. The knowledge of this subject is very essential for

an engineer in designing the various parts of a machine.

 

Sub- Divisions of TOM

 

1. Kinematics: It deals with the relative motion between the various parts of the machines.

2. Dynamics: It deals with the forces and their effects while acting upon the machine parts in Motion.

3. Kinetics: It deals with the inertia forces which arise from the combined effect of the mass and motion of the machine parts.

4. Statics: It deals with the forces and their effects while the machine parts are at rest. The mass of the parts is assumed to be negligible.

 

DEFINITIONS RELATED TO TOM

 

• Kinematic Link

Kinematic link each part of a machine, which moves relative to some other part, is known as a kinematic link.

A link may consist of several parts, which are rigidly fastened together so that they do not

move relative to another part. For example, in a reciprocating steam engine, piston, piston

rod  and  crosshead  constitute  one  link;  connecting  rod  with  big  and  small  end  bearings

constitute a second link; crank, crankshaft, and flywheel a third link and the cylinder, engine

frame and main bearings a fourth link.

 

• Kinematic Pair

Kinematic pair: The two links of a machine, when in contact with each other, are said to form a pair. If the relative  motion  between  them  is  completely  or  successfully  constrained  (i.e.  in  a  definite direction), the pair is known as kinematic pair

 

• Kinematic Chain

A kinematic chain is an assembly of links in which the relative motions of the links are possible

and the motion of each relative to the other